Augmentation of peripheral venous diameter for ultrasound-guided peripheral intravenous line insertion.

OBJECTIVES: Ultrasound-guided intravenous line placement is utilized often in the emergency department for venous access in patients whose veins are difficult to cannulate by traditional methods. This study aims to identify specific interventions that will augment venous cross-sectional area. METHODS: Residents and medical students volunteers each had their basilic vein identified using the linear array probe on an ultrasound. The area of the vein was measured with no intervention with the arm positioned parallel to the floor as well as approximately 45 degrees below the level of the bed. These two positions were repeated with the following interventions: one standard rubber tourniquet applied proximal to the vein measurement, an additional rubber tourniquet applied proximal to first tourniquet, blood pressure cuff inflated to between 160 and 200 mmHg applied proximal to the vein, CAT battle tourniquet application proximal to measurement site, and soaked warm towel applied to brachium for up to one minute. The primary outcome was to evaluate the increase in venous cross-sectional area from the baseline measurement after the interventions. RESULTS: We had 41 participants in this study. All interventions were statistically significant in increasing venous cross-sectional area as compared to no intervention, with the most significant augmentation being from the CAT battle tourniquet (mean change +7.32 mm2, 95% CI, 5.73-8.91 mm2) . The change in position of the arm, was not statistically significant for any intervention except for the CAT tourniquet (mean change -1.74 mm2, 95% CI, -0.54 to -2.93 mm2). There was no significant difference between two tourniquets and blood pressure cuff (mean change +0.58 mm2, 95% CI, -1.13 to +2.29 mm2), but there was a significant increase in cross-sectional area with CAT tourniquet use compared to blood pressure cuff (mean change +1.62 mm2, 95% CI, 0.29-2.95 mm2). Lastly, two tourniquets increased cross- sectional area compared to one tourniquet (mean change +2.20 mm2, 95% CI, 1.14 - +3.26 mm2). CONCLUSIONS: This study identified several potential interventions for maximizing venous cross-sectional area on ultrasound. All the tested interventions resulted in statistically significant increases in cross-sectional area. Arm positioning did not show significant changes in most interventions, with the exception of the CAT tourniquet. Further studies should be performed on how these maneuvers affect success in ultrasound-guided intravenous line placement.

The Significance of Inflow Artery and Tourniquet Derived Cephalic Vein Diameters on Predicting Successful Use and Patency of Arteriovenous Fistulas for Haemodialysis.

OBJECTIVE: To investigate the significance of inflow artery and cephalic vein diameters on predicting patency of radiocephalic and brachiocephalic arteriovenous fistulas (AVFs). DESIGN: Single centre study with retrospective analysis of prospectively collected data between November 2010 and July 2015. METHODS: A detailed history and physical examination was undertaken, including age, gender, history and duration of haemodialysis, cause of chronic kidney disease, and the presence of comorbidities/risk factors. Pre-operative arterial and venous upper extremity mapping was performed and inner vessel diameter was recorded, using a tourniquet for the veins. Outcome measures included AVF use (functionality), primary, primary assisted, secondary, and functional secondary patency. RESULTS: One hundred and thirty five AVFs (57 and 78 radiocephalic and brachiocephalic AVFs, respectively) were constructed and followed up for 5 years. A cephalic vein diameter <4.3 mm (lower three quartiles) was the single independent predictor of inferior secondary and also functional secondary patency of radiocephalic AVFs (p = .02, HR 11.2, 95% CI 1.44-90.9). A brachial artery diameter ≤4.1 mm (lowest quartile) was an independent predictor of AVF functionality (57% vs. 83% for larger arteries, p = .017), and inferior primary, primary assisted, secondary, and functional secondary patency of brachiocephalic AVFs (primary assisted patency 21.9% vs. 55.9% at 3 years, p = .001/log-rank test, HR 3.1, p = .002/Cox regression). The presence of lower extremity PAD or use of dual antithrombotics was also independently associated with an inferior secondary patency. The number of risk factors (brachial artery diameter ≤4.1 mm, PAD, and use of dual antithrombotics) demonstrated risk stratification capabilities for functional secondary patency. CONCLUSIONS: Among patients undergoing radiocephalic AVFs, a tourniquet derived cephalic vein diameter <4.3 mm was the single independent predictor of inferior secondary and functional secondary patency. Among patients undergoing brachiocephalic AVFs, all patency rates were inferior in the presence of a brachial artery diameter ≤4.1 mm and secondary patency was inferior in the presence of multiple risk factors.

Multi-model genome-wide association studies of leaf anatomical traits and vein architecture in rice.

Introduction: The anatomy of rice leaves is closely related to photosynthesis and grain yield. Therefore, exploring insight into the quantitative trait loci (QTLs) and alleles related to rice flag leaf anatomical and vein traits is vital for rice improvement. Methods: Here, we aimed to explore the genetic architecture of eight flag leaf traits using one single-locus model; mixed-linear model (MLM), and two multi-locus models; fixed and random model circulating probability unification (FarmCPU) and Bayesian information and linkage disequilibrium iteratively nested keyway (BLINK). We performed multi-model GWAS using 329 rice accessions of RDP1 with 700K single-nucleotide polymorphisms (SNPs) markers. Results: The phenotypic correlation results indicated that rice flag leaf thickness was strongly correlated with leaf mesophyll cells layer (ML) and thickness of both major and minor veins. All three models were able to identify several significant loci associated with the traits. MLM identified three non-synonymous SNPs near NARROW LEAF 1 (NAL1) in association with ML and the distance between minor veins (IVD) traits. Discussion: Several numbers of significant SNPs associated with known gene function in leaf development and yield traits were detected by multi-model GWAS performed in this study. Our findings indicate that flag leaf traits could be improved via molecular breeding and can be one of the targets in high-yield rice development.

Impact of venous outflow tract on survival of osteocutaneous free fibula flaps for mandibular reconstruction: A 14-year review.

BACKGROUND: The principle reconstructive modality for segmental mandibulectomy defects is the osteocutaneous free fibula flap. Preoperative CT angiography has been recommended to assess the quality of arterial inflow to the flap and donor limb. However, the impact of the venous system on flap viability has not been explored. METHODS: A retrospective review of all patients undergoing free fibula flap mandible reconstruction was performed at a single tertiary cancer center from 2002 to 2015. Overall complications, including operative reexploration and total flap losses, were evaluated. RESULTS: One hundred seven patients underwent free fibula flap reconstruction of the mandible. Nine patients underwent multiple free flaps and were excluded from this study. Of the remaining 98 patients, 8 patients required operative exploration for microvascular compromise. All patients were found to have venous thrombosis. There were 3 total flaps losses with a salvage rate of 62.5% and overall flap survival of 96.9%. The size of the vena comitantes in the compromised flaps were significantly larger than those of the remaining patients (4.4 mm vs 3.1 mm; P < .0001). Although the total operative times were similar between the 2 groups (585.2 minutes vs 563.3 minutes), the ischemia time was significantly shorter in those cases that required operative takeback (76.5 minutes vs 104.0 minutes; P < .04). CONCLUSION: Venous thrombosis of free fibula flaps is more common than arterial thrombosis. Venous stasis in larger vena comitantes may be a contributing factor to microvascular compromise. Anticoagulation and/or handsewn anastomosis may be beneficial if the veins are larger than 4.0 mm in size.

Comparison of the effect of the Trendelenburg and passive leg raising positions on internal jugular vein size in critically ill patients.

Central vein catheterization is a common procedure performed on patients under intensive care. The safe and successful placement of the central venous catheter depends on vein size. Although used for this purpose, the Trendelenburg position can be hazardous in some patients. The aim of this study was to compare the effects of the Trendelenburg and passive leg raising (PLR) positions on the size of the right internal jugular vein (IJV) in mechanically ventilated patients under intensive care. Seventy-eight mechanically ventilated patients under intensive care were included into the study. Sonographic images of the right IJV were recorded in supine (control), 10° Trendelenburg and 40° PLR positions. Anterior-posterior and transverse diameter, cross-sectional area (CSA), and depth were calculated from the recorded images. The size of the right IJV (CSA, transverse and vertical diameters) was significantly larger in the Trendelenburg and PLR positions than in supine position. An increase of 26% in the IJV CSA was obtained in the Trendelenburg position and 23% in the PLR position, compared to the supine position. There was no significant difference between the measurements obtained from the Trendelenburg and PLR positions. The study shows that the Trendelenburg and PLR positions increase the size of the IJV to a similar extent in mechanically ventilated patients under intensive care.